1. Field of the Invention
This invention relates to apparatus for cleansing stack gases, and more particularly to a liquid spray apparatus for continuously washing or scrubbing stack gases for removing solid and gaseous pollutants therefrom.
2. Description of the Prior Art
A major source of air pollution is the smoke and noxious gases which are discharged directly into the atmosphere from smoke stacks. Many of the stack gases, particularly those from incinerators and certain industrial processes, contain substantial quantities of soluble gaseous pollutants and entrain substantial quantities of solid particulate matter which may be washed, or scrubbed, from the stack gas. Numerous washing devices have been developed and used for removing the particulate and soluble gaseous pollutants from stack gases, with these prior devices generally employing a system of nozzles for spraying a wash liquid directly into the gas stream to absorb or entrain the contaminates. The contaminated liquid is then collected from the gas stream to thereby prevent the pollutants from being discharged into the atmosphere.
Discharging the necessary volume of scrubbing liquid into the flow of gases in a stack will inherently materially alter the operating characteristics of the stack. Thus, a substantial pressure drop will result in the stack due both to the energy directly absorbed from the stack gas stream by the spray liquid and by the substantial reduction in temperature resulting from spraying the liquid into the normally high temperature gas stream. The resultant modification of stack flow characteristics will in most cases adversely effect the primary process whether it be the burning of trash in an incinerator, conventional fuels in a furnace, or other industrial process.
Various attempts have been made to solve the problems created by the introduction of scrubbing liquid into a stack gas stream, including use of means for inducing an increased stack velocity to compensate for reductions caused by the ingestion of liquid into the gaseous stream. These devices have, however, generally required special design of the stack and have not generally been readily adaptable to existing, conventionally designed stacks. Furthermore, these prior devices have generally been relatively expensive to manufacture and have been difficult to maintain and operate due to the relative inaccessibility of much of the apparatus.